The following disclosure relates generally to communications systems and, more particularly, to Ec/Io access screening in a code division multiple access (“CDMA”) network.
Echo is the ratio of received pilot energy (Ec) to total received energy or the total power spectral density (Io) expressed in dB. Ec/Io is a CDMA-only reading and is sometimes referred to as pilot strength. A ratio of −10 dB to −14 dB is normal; ratios higher than −14 dB are progressively worse to −31.5 dB, at which power readings are immeasurable.
It has been noted that, for a live customer market, approximately 25% of all origination access failures occur when the active pilot strength is low and approximately 13% of all origination drops occur under these conditions. Screening based solely on the Echo of the primary or reference pilot result in a higher number of calls being redirected without a significant increase in performance.